Charged particle beam arrangements are widely used in a plurality of industrial fields, including, but not limited to, inspection of semiconductor devices and electronic circuits during manufacturing, exposure systems for lithography, detecting devices, defect inspection tools, and testing systems for integrated circuits. Semiconductor technologies have created a high demand for structuring and probing specimens in the nanometer or even in the sub-nanometer scale. Process control, inspection and/or structuring is often based on the use of charged particle arrangements providing charged particle beams, e.g. electron beams, which are generated and focused in charged particle beam arrangements, such as electron microscopes or electron beam pattern generators.
High performance inspection devices using charged particle beams such as scanning electron microscopes (SEM) offer superior spatial resolution compared to, e.g. photon beam arrangements because their probing wavelengths are shorter than the wavelengths of light beams. For instance in case of an SEM, the primary electron (PE) beam generates particles like secondary electrons (SE) and/or backscattered electrons (BSE) that can be used to image and analyze a specimen. In particular, a scanning electron microscope, SEM, can be used for high throughput, high resolution imaging process defects on wafers.
Prior art SEM columns may provide high-resolution of specimen structures. Wafer inspection SEM can be used for high throughput, high resolution imaging of process defects on a specimen such as a wafer. Many instruments use either electrostatic or compound electric-magnetic lenses to focus the primary beam onto the specimen. There is a need for inspection devices operating at a spatial resolution in the nanometer and sub-nanometer range at low landing energies.
As the features on a wafer become smaller the requirements of the resolution and throughput increase. For high resolution imaging devices based on electron optics systems, e.g. high resolution versus high probe current, and large image field versus small pixel size, respectively, are contradicting considerations. An electron optical system of a scanning electron microscope, SEM, which can fulfill these contradicting requirements, is beneficial.